(a) Field of the Invention
The present invention relates to a process for preparing polymerized toner, specifically to a process for preparing polymerized toner that can realize narrow particle size distribution, high transcription efficiency and uniform image by using calcium phosphate as an aqueous dispersion stabilizer and a polymer charge control agent having a specific molecular weight range during suspension polymerization.
(b) Description of the Related Art
Toner refers to paint that is used for development of electronic photos and an electrostatic printer, a copier, etc., and can be transcribed and adhered to a transcription material to form a desired pattern. Recently, as preparation of a document using a computer has been generalized, demand for an image formation device such as a printer is rapidly increasing, and thus, toner use amount is also increased.
In general, a process for preparing toner includes a process using pulverization and a process using polymerization. The process using pulverization, which is most widely known, simultaneously introduces resin and pigment through a melting-mixing process, and after melting-mixing or extrusion, pulverizes and distributes to prepare toner particles. However, toner particles prepared by this process have wide particle size distribution, and have very irregular shape such as sharp edge, etc., and thus chargeabilty or flowability is not good.
To solve this problem, a process for preparing spherical toner particles by polymerization has been suggested. As the process for preparing toner by polymerization, emulsion polymerization (aggregation process) and suspension polymerization are known, and the emulsion polymerization is difficult to control particle size distribution and has a problem of reproducibility of prepared toner quality, and thus, a process for preparing toner by suspension polymerization is more favored.
However, the process by suspension polymerization involves a process of dispersing a monomer mixture in the form of droplets through homogenization with an aqueous dispersion and polymerizing, during which process, it is difficult to prepare particles having narrow particle size distribution. And, the toner particles produced by the suspension polymerization should have very uniform chargeability so as to realize high transcription efficiency and uniform image.